The contract network of clinical trial sites will evaluate systematically the safety and efficacy of new female contraceptive drugs and devices as well as drug treatments of gynecologic conditions in Phase I, II, and III clinical trials. The study design will be specified in each Request for Task Order Proposals. The results of these clinical trials would be the basis for advancing candidate drugs and devices through development, with the ultimate goal of submission to the FDA in support of a New Drug Application (NDA), Premarket notification 510k, Premarket Approval (PMA) or Investigational Device Exemptions (IDE). Based upon site capabilities, the Principal Investigator (and other site personnel as appropriate) shall participate in the development of protocols in cooperation with personnel from the Statistical and Clinical Coordinating Center and with NICHD program personnel. The candidate protocols, drugs or devices to be evaluated clinically under this contract shall be selected by the NICHD with consultation from the Scientific Advisory Committee of the CCTN. The NICHD has a mission to develop safe and effective contraceptives for women, including obese women. Obesity is the number one public health issue facing the US population and is independent risk factor for venous thromboembolism (VTE). Therefore, there is a public health need to develop effective contraception for obese woman that does not increase the risk of VTE. The Nes/E2 ring has the potential to provide effective long term contraception without the need for daily intervention. The proposed study will be conducted in women of reproductive age in order to evaluate contraceptive efficacy, pharmacokinetics, bleeding patterns, and the safety and side effects of this new contraceptive product. The enrolled subjects will be randomized into three treatment groups who will receive rings containing Nes in combination with different doses of E2. The objectives is to obtain valid and reliable data to determine the contraceptive effectiveness, pharmacokinetics, bleeding patterns, side effects and safety of vaginal rings containing Nes and Es in women of reproductive age to identify a dose that can provide reliable contraception and acceptable bleeding patterns for up to 6 months of use.The proposed study will evaluate contraceptive efficacy , pharmacokinetics, bleeding patterns and safety and side effects of a Nestorone & estradiol ring for women.